As is known to those familiar with disc brakes, the relatively high temperatures, to which the disc braking surfaces are subjected during braking, cause considerable expansion and contraction, and consequently, distortion, of the disc which may result in eventual failure. Various methods for accommodating disc expansion and contraction are known, one being to radially elongate the mounting bolt holes, that is, the holes for the bolts by which the disc is secured to the mounting hub. It has been found with this arrangement, however, that the relative movement between the portions of the disc having the elongated holes and the stationary or fixed bolt heads (caused by expansion and contraction of the disc) results in wear between the bolt head and the disc surface, thus resulting in loosening of the bolts and eventual failure of the disc.